I've just had a look at my Dad's service record. 9 stone 7lb when he enlisted in 1943 and 11 stone 6lb at discharge in 1947. Apparently post-war life in BAOR wasn't all bad.

There is no mention of what he weighed in The Netherlands in 1944/45.

I believe actually that the British Army had gone back to its normal peacetime activity of plenty of sport by 1947.